Chapter 13 Experiments Flashcards
Mating Systems in Red Warblers
RQ 1: How does habitat quality
(amount of food resources) correlate with
mating system?
RQ 2: How are habitat quality
and mating system related to the level of male
care?
M: estimate. variety of habitats, poor, medium, high → characterised male care →created phylogeny
R:POOR Quality → monogamy & high parental care
MEDIUM + GOOD quality →Polygyny + promiscuity + reduced male care
C: supports the model of Elkan + Oring → habitats w/ limited resources favour monogamy + high levels of male care
California Mouse Monogamy
O: California mice are monogamous
(rare in mammals)
RQ: How does male care affect reproductive success in this species?
P: Reproductive success will be low if paternal care is absent
M:
- Checked females for reproductive condition (pregnant or
lactating) and weighed
- Removed some males from monogamous pair within 3 days of litters birth
- Estimated number of young born to each female by comparing her weight loss
- Used a formula to convert body mass loss to offspring number
- Compared offspring number and success (emergence from
burrow) to control pairs that contained a male
R: Both group → similar # of young, families w/ father removed → lower offspring success
C: Male care enhances in reproductive success in monogamous mice
Monogamy + Biparental Care in Poison Frogs
R. Imitator → monogamous, R. Variabilis → promiscuous
RQ: Why does Imit. have a mono. mating system while variba. is promiscuous
H: When resources are limited → monogamy evolves b/c biparental care is required to successfully raise offspring
P: Tadpoles in resource limited small pools will exhibit high survivorship ONLY with biparental care
M: Manip. pool size → tadpoles wither placed in small / large pool + no female feeding Control: indiv. placed in small poll = received female feed → monitored growth for 3 weeks + mortality
R: Both → large pools = high growth + survivorship
Small pools: no parental care → both species = low growth rate + survior.
Controls in small pools w/ biparental care = high growth rate + sur
C: Need for biparental care in R. Imit → strong selection that favours monogamy in this species
Monogamy without biparental care - Snapping Shrimp
RQ: Why are snapping shrimp monogamous when males provide no care?
H: Territorial Cooperation H + Mate guarding H
M: Resident shrimp constructed a burrow used for
nesting
Territory Cooperation Experiment:
Allowed single females and paired females to guard burrow from a same-sex (size matched) intruder
Mate Guarding Experiment:
Allowed males to chose females either close to sexual receptivity (high-value) or not close to sexual receptivity (low-value)
R: Terr: F paired w/ M = more succes in burrow def. than solitary F
Mate guard: M chose to guard sexually-recpetive F more than non-sex
Shrimp Experiment further developed - exploring the mate guarding hypothesis
RQ: How are males able todetermine female sexual receptivity
M: Presented a M flowing from two arms of a Y- maze
- Treatment arm contained a shrimp
- Control arm contained untreated water
Seven different treatments - varied the sex of the shrimp and its molting state water with pre-molt, inter-molt, and post-molt males and females and a control (untreated water)
Molting = shed their exoskeleton so to develop a larger one.
- Recorded behaviour
R: M only moved toward water that contained pre-molt female water
OVERALL CONCLUSION - BOTH STUDIES
M are able to determine female sexual receptivity and are attracted to females close to sexual receptivity
Territorial cooperation and mate guarding have favoured monogamy in snapping shrimp
Female Defense polygyny in horses
O: Feral horses live in social units, bands, with one male and up to a dozen females
RQ: Do male horses defend females directly (female defense polygyny) or the resources that females seek (resource defense polygyny)?
M: Recorded location of bands over 3 -year period, Recorded social behaviours, particularly aggressive interactions b/w M from different bands - Plotted the home range used by each band
R: Bands overlapped in their home ranges with no evidence of exclusive defense of territories
- Males defended (their) females from other males
- All bands used the same geographic areas over time
- Males defend females directly and so display female defense polygyny
Resource Defense Polygyny in Blackbirds
O: Blackbirds exhibit variation in their mating system
RQ: Why do some blackbirds mate monogamously while others mate polygynously?
H: The polygyny threshold model explains variation in polygyny
P: Polygyny should only be observed on high-quality territories
M: F given choice to mate mono, in low quality terr. / poly. in high Quality, added nesting platforms over water (HQ)→ for 1 male , + nest. plat. over land (LQ) other male + removed F, gave new F the 2 mating options - recorded behaviour
R: in 12/14 male dyads → F picked HQ terr + mate poly → higher reprod. success
C: TQ affects observ. mating system → pred. by polygyny threshold model
Resource Defense polygyny carrion beetle
O: M defend small vertebrate carcasses + F Larvae feed on it → observe m-m aggression
RQ: Does the variation in aggression b/w sexes indicate that these beetles exhibit resource defense polygyny
M: 2 M + @ F → are w/ peices of meat - indiv varied in size → Large M = dom. over small M = winning fights → F mated w/ both
- Recorded mating success of all indiv. using DNA of offspring
R: Dominants removed → territ remained unoccupied → subordinates moved away, subordinated removed →other subordinate added vacant space to their
C: Results support the hot shot hypoth
Lekking behaviour in Great Snipe
- Breeding season →M display leks for hours
- observed leks → male interactions to determine dom.
- Each lek → couple of dom. indiv. = won most interac.
- Dom. indiv. = highest display rates + mating sucess on each lek + mated poly
- Dom leks removed → territory = unoccupied
- Subordin removed → neighbour took over
- Supported the hotshot theory
Peafowl Leks
RQ: Why do male peafowl aggregate on leks?
M: Majority of males aggregated, some were floaters, Recorded male-male interactions, male display rates, female visitation rates, and mating success of 29 males on a leks
- Removed the M for 2 weeks and recorded the effect on M+F
R: Floater males quickly settled on the sites of removed males and began displaying, Display rates of new males similar to prior males, # of F visits to a display site was similar before and after a M was removed
C: Results supprt the hotspot hypoth - F prefer to mate w/ M close to feeding site
Polyandry in European Badgers
O: badgers live in soical groups of up to 2 doz. indiv. + contain multiple reprod. active M+F
RQ: Are European badgers plygynandrous?
M:Over a 17-year period captured and uniquely marked individuals in population, Took blood samples from over 300 cubs to determine parentage, Recorded social associations of groups
R: Social groups avg 6 adult M + F, 31% of F bred successfully each year - w/i social groups - multiple M + F reproduced w/i single breeding attempt
Scramble population + Seaweed Flies
- indiv compete indirectly to secure copulations w/ multiple mates
- Flies live + breed in decaying seaweed on beaches - engage in no courtship behaviour + males copulate w/ F as soon as they encounter them
Promiscuity and scramble competition: red squirrels
O: M + F defend sep. territ. →F receptive for 1 day + relax territ. defense - multipl M visit their Territ.
RQ: Do red squirrels display promiscuity, characterized by scramble competition where individuals compete with one another to obtain copulations with multiple mates ?
M:Captured and marked individuals with ear tags - had radio transmitters for monitoring movement
-Collected tissue samples for DNA paternity analysis
- Followed females on their single day of sexual receptivity and recorded “mating chases” and copulations
R: F copulated with avg of 5.8 M, over 780% of litters - sired by multiple males
C: Indicated promiscuous mating system w/ scramble competition
Extra Pair Mating in Juncos
RQ: Why do female juncos engage in extra-pair copulations?
H: F can enhance the fitness of their offspring via extra-pair matings
P: Offspring from extra-pair matings will have higher fitness than within-pair offspring
M: Used long term data set as a population, DNA analyses since 1990 allowed determination of paternity, examined data of over 2,200 nestlings
R: No difference in fledgling success, EPY produced more grandoffspring than within-pair young
C: Fitness of F offspring from extra-pair matings is higher than that of within pair young - supports Genetic Quality Hypothesis
Marmot Extra Pair Mating
O: Marmots live in social groups with dominant male and female (breeding pair) + subordinate offspring - Extra pair matings are common
RQ: Why do female marmots engage in extra-pair copulations?
H: Females can enhance the fitness of their offspring
P: EPY will have higher fitness than within-pair young
M: Trapped, sexed, + marked individuals, collected hair or tissue for DNA analysis, transponders to determine locations, social status of all individuals by observing dominance interactions - Determined paternity of 220 offspring
R: 45/ 220 offsrping -extra pair mating (not w/ dom male)
EPoffspring = higher survivorship + prob of becoming domthan within pair young
- survivorship + related to lvel of heterozygosity
C: F can improve their fitness by seeking extra pair partners yield more heterozygous offspring than their social mate can
